title: Interaction of intense femtosecond laser pulses with KDP and DKDP crystals in the short wavelength regime.
abstract: We investigate the electronic photo-excitation and relaxation mechanisms involved in the optical breakdown of potassium dihydrogen phosphate crystal (KH2PO4) and its deuterated form. The dynamics and spectroscopic properties of electron-hole pair formation are investigated using time-resolved measurement of the dielectric function, and luminescence spectroscopy. The non-common mechanical and electronic characteristics of these dielectric materials are revealed by the particular structure of ablation craters and also by the complex dynamics observed in the relaxation of excited carriers. This relaxation occurs in two steps, and varies with the initial carrier density and thus with the laser intensity. We show that the defect states play a key role in the excitation pathways, and also determine the relaxation stage. The latter also depends upon the initial amount of energy of the electron-hole pair after photo-excitation. A model based on kinetic equations describing the evolution of the different level populations allows us to successfully interpret and reproduce the experimental data.
authors.affiliation: Université de Bordeaux-CNRS-CEA, Centre Laser Intenses et Applications UMR 5107, 351 Cours de la Libération, F-33405 Talence, France.
authors.forename: Guillaume
authors.initials: G
authors.lastname: Duchateau
authors.forename: Ghita
authors.initials: G
authors.lastname: Geoffroy
authors.forename: Andrei
authors.initials: A
authors.lastname: Belsky
authors.forename: Nikita
authors.initials: N
authors.lastname: Fedorov
authors.forename: Patrick
authors.initials: P
authors.lastname: Martin
authors.forename: Stéphane
authors.initials: S
authors.lastname: Guizard